四级练习2013.09.10
[audio]http://sound.yywz123.com/tingbbs/cet4/cet420130910.mp3[/audio]Better to avoid the unstable hammocks altogether, since (1)________________________, and flesh-eating plants that feed on mosquitoes. Water in the Okefenokee is dark, like tea that has steeped a long time. The color comes from tannin that seeps from towering cypress trees draped in Spanish moss.
Every once in a while, the rangers must crack down on reckless pilots of airboats that skim across the swamp, endangering themselves and others and tearing up delicate foliage. And developers, logging companies, and strip-mine operators on the edge of the swamp can easily upset the (2)________________________.
The Okefenokee, which is already nearly choked with plants, would probably fill in, dry up, and become just another cypress and pine forest were it not for range fires that come along every once in a while and (3)_______________________. So the water in this protected National Wildlife Refuge keeps moving slowly, very slowly.
**** Hidden Message ***** their fill with snakes and occasional bears
the delicate balance of nature in the area
burn out vegetation
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